Will average temperature increases mean nicer, warmer weather, perhaps hot enough that we use our air conditioners more? Or will they mean no snow on the Rockies, a dried up Lake Manitoba and  as one scientist in the third episode of ClimateWatch predicts  "a nasty change in the frequency and severity of extreme weather events?"

Peter Bein says...

Most scientists are worried. A global average warming of one or two degrees, they say, doesn't mean that climate warming will be nice and gradual, or that all areas will experience warming in the same way. For instance, the prairies and the western Arctic have experienced warmer conditions on average, but in Eastern Canada and the Eastern Canadian Arctic average temperature appears to be decreasing.

As well, within any 10 or 50-year period, there may be long spells of divergence from the warming trend. Weather could simply swing more wildly than it has previously.

Scientists looking back through geological history say the rate of change in temperature is unprecedented.

David Schindler says...

David Schindler, Killam Profesor of Ecology at the University of Alberta, says that during the mid-Holocene Period 5000-6000 years ago, with global average temperatures only a degree warmer than now, Lake Manitoba was totally dry.

"The past is your guide to the future," one of his colleagues adds.

Schindler invites a comparison between conditions in the area around Lethbridge and the area around Fort Chipewyan, where the average annual precipitation is the same but one area is virtual desert, while the other is mostly wetlands. The difference, he says, is the dramatically different rate of evaporation caused by a long-term average temperature difference of just two degrees.

In his mind, with a five-degree change forecasted for the next 100 years, that means there are "big implications for climate warming."

Don MacIver says...

Others might celebrate an expected increase in biodiversity in Canada. After all, with more heat, biodiversity will rise. Will that mean richer biodiversity? Don MacIver, Science Advisor with Environment Canada in Downsview, Ontario, warns that native biodiversity will lose and the increase will come from invasions.

In the Arctic, permafrost melting has created what researcher Peter Bein whimsically calls "drunk forests," where trees cannot stand up and disease is rampant. Studies in the boreal forest have shown an average 10-day increase in tree growing season. That should produce more growth, but unfortunately the trees can't get enough moisture to keep up, so there is actually die-back.

The viable range for most species of plants and animals is moving northward. But stands of trees need to seed, mature, reseed and mature in order to move, and may not be able to migrate northward fast enough to keep up with the expected rate of climate change.

"We might be asking, under global warming, plants and animals to move 10 times faster than they did as they followed the ice sheet 10,000 years ago," points out Jay Malcolm, Assistant Professor in the Faculty of Forestry at the University of Toronto. "Many organisms can't keep up with it."

melting of permafrost and the drying of wetlands, for example, may lead to the release of methane and carbon dioxide stored or sequestered in those systems, thereby stimulating further warming.

Impacts are expected to occur sooner, and more severely in northern latitudes. They have already been observed by scientists and northern residents in the form of permafrost thawing and slumping, open water where formerly there was consistent ice cover, late freeze-up, earlier break-up and generally more unpredictable conditions for hunting and traveling.

But scientists also point out that variability is characteristic of the Arctic, and that it is difficult to say whether northern climate phenomena represent normal variability or human-induced climate change.

What about other regions, other impacts? What about the prairies, where warmer temperatures might be welcome, where growing conditions could improve?

Again, scientists warn that warming will reduce the available supply of water, that the weather will become more variable, that the frequency and severity of drought may increase, and that precipitation will occur in intense outbursts, so that localized flooding will be a threat alongside the drought.

Daniel Scott says...

An expanded range for agriculture, with improved climatic conditions for growing crops, might not occur in the short term as optimists might hope. Prairie agriculture thrives thanks to grassland soils built up over thousands of years. "The reality is contentious," says one scientist interviewed for ClimateWatch. "You don't instantaneously have soils that produce agriculture."

Climate variability might present a whole series of different questions and concerns in more densely populated parts of Canada. For instance, an expected one meter drop in the level of the Great Lakes could have huge impacts on drinking water supply or sewage infrastructure. Expected increases in temperature, and periods of elevated temperatures sustained over longer periods, pose serious air quality risks in a region already struggling with smog.

Will society make the right adaptation choices, or will it continue to make development decisions that exacerbate the problem and expose the population to more extreme risks?
Will humans make the revolutionary social and economic shift away from combustion of fossil fuels? Will we develop some previously unimagined technology that reduces greenhouse gases dramatically or enables communities to endure in the face of harsher conditions?

Humans are an amazingly resourceful species. We can redesign cities and build dikes to hold back rising oceans, but what will the world be like if more fragile ecosystems fail? As one scientist philosophizes, civilization itself could collapse and the individuals who are strongest and most resourceful may survive at the expense of the weakest.

Episode 3 of ClimateWatch takes a compelling look at the impacts of global warming. If the past is the guide to the future, then we have some interesting, perhaps frightening, times ahead.

The following voices (and more) are featured in Impacts, Episode Three of the ClimateWatch audio series

ClimateWatch is a series of audio documentaries and public service messages about Earth's atmosphere, climate change and global warming. A five CD set of appx. hour-long productions is available to university and community radio stations and to educational and academic users. Orders for individual titles and the boxed set can be ordered through this web site.